Electrical code translators



April 21, 1964 A. FREEDMAN 3,130,398

ELECTRICAL CODE TRANSLATORS Filed Dec. 22, 1958 2 Sheets-Sheet 1 E I [mL14 D,

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m VENT ARYE LE/B FRESDMA/V ATTORNEY April 21, 1964 A. 1.v FREEDMANELECTRICAL CODE TRANSLATORS 2 Sheets-Sheet 2 Filed Dec. 22, 1958 MWENTORARYE LE/B FREED/"IAN QM K M.

ATTORNEY United States Patent 3,130,398 ELECTRICAL CODE TRANSLATORS AryeLeib Freedman, Stevenage, England, assignor to Ericsson TelephonesLimited, London, England, a

British company Filed Dec. 22, 1958, Ser. No. 782,021 Claims priority,application Great Britain Jan. 2, 1958 8 Claims. (Cl. 340-347) Thepresent invention relates to electrical code translators such, forexample, as are used in telephone exchanges, the translators being ofthe type comprising a plurality of groups of cores of ferro-magneticmaterial, each core being provided with a separate output wiremagnetically coupled thereto and a plurality of input Wires beingprovided each of which is magnetically coupled to a plurality of coresselected from different groups respectively of cores.

In such translators as normally operated, a signal applied to an inputwire induces output signals in the output wires of each of the coresmagnetically coupled to the input wire.

Thus, for example, a translator may comprise four groups of cores, eachhaving ten cores representing the numbers 0, 1, 2, 3, 4, 5, 6, 7, 8, 9.Different input wires may thread different sets of cores, each havingfour cores, one from each group. A selection of four cores, one fromeach of the four groups, corresponds to the four digits of a four figurenumber. On the application of an appropriate signal to one of the inputwires output signals are provided in four output wires and represent afour figure decimal number. Often the cores are made in the form ofrings and the input wires are loosely threaded through the rings toeffect the magnetic coupling. Such an arrangement has been foundparticularly useful since a change of the number corresponding to agiven input wire may readily be effected. Thus the wire is pulled out ofone set of cores and threaded through a new set of cores to effect therequired change.

There is sometimes need for a translator of the type defined whereinprovision is made for controlling the times at which output signals areprovided from the different groups of cores and it is an object of thepresent invention to provide such a translator.

According to the present invention an electrical code translator of thetype defined comprises a plurality of control wires, magneticallycoupled to all the cores of the groups of cores respectively, and acontrol circuit is connected to the control wires, the control circuitbeing adapted to provide currents in predetermined control wires orcombinations of control wires for selectively allowing the generation ofoutput signals in the output wires of the different groups of cores, orfor selectively causing the generation of output signals in output wiresof the different groups of cores following the application of an inputsignal to an input wire.

In this specification the term switchable core means a member offerro-magnetic material having a hysteresis loop of such shape that onthe application and removal of a magnetic field or magnetomotive forceof appropriate sense to change the state of magnetisation of thematerial from one to the other of the two stable states, hereinafterreferred to respectively as the datum state and the alternative state,existing in zero external field after saturation of the core in twoopposite senses respectively, as the magnitude of the field of theappropriate sense is increased from zero to a first value the fluxwithin the material changes by a relatively small amount, as themagnitude of the field is increased beyond the first value by a valuesmall compared with the first value a relatively large flux change,accompanied by change of sign, occurs and as the magnitude of the fieldis thereafter decreased to zero only a relatively small flux changeoccurs.

Materials having hysteresis loops of the shape known in the art asrectangular are suitable materials. A rectangular hysteresis loop may besaid to be one for which the remanent magnetic flux in the datum stateand the alternative state is or more of the flux at saturation. Theabove definition is not however limited to cores of such materials.

Thus an input signal may be applied to an input wire and output signalsbe obtained in sequence from the cores with which the input wire ismagnetically coupled. If the groups of cores correspond to the digits ofa number the signals representing the digits of the number correspondingto a given input wire may be provided in succession.

The invention can achieve the aforementioned object by making use of thesaturation effect of ferro-magnetic cores by applying currents incontrol wires of magnitude sufficient to produce magnetomotive forces tosaturate all the cores in those groups with which the wires areassociated. The input signals may be applied as pulses of sense such asto produce magnetomotive forces to magne tise, or tend to magnetise, thecores in the same sense as the currents in the control wires. A pulse inan input wire will only produce an output signal in the output wire of acore not in a group of cores whose control wire is energised by thecontrol circuit. A succession of input pulses may be provided in aninput Wire and the different control wires be de-energised in turn, withthe other control wires energised, i.e., with N groups of cores and Nrespective control windings, the control wires are successivelyde-energised by energising in succession N different combinations ofcontrol wires consisting of all said controls wires except one. Thus thedigits of a number may be derived in succession. The succession of inputpulses may be provided by a rectified alternating current. In analternative form, unrectified alternating current may be applied in aninput wire, the currents in the control wires being of magnitudes greatenough to take the cores sufficiently beyond saturation, to prevent anappreciable output signal being induced by the alternating current.

The invention may be carried into effect in a variety of ways when usingswitchable cores.

A current of half the magnitude necessary to switch a core may beapplied to an input wire as the input signal and a further current ofhalf the magnitude necessary to switch the core be applied by thecontrol circuit to the control wire associated with a group of coresfrom which an output signal is required. A similar effect may beachieved by applying an inhibiting current in an inhibit wiremagnetically coupled to all the cores of magnitude sufficient to cancelthe effect of the current applied as an input signal to an input wire,which current is made of magnitude sufficient by itself to switch acore. The control circuit applies a current in the control wireassociated with a group of cores from which an output signal isrequired, the current being of a magnitude sufficient to switch the coreof the group of cores for which the effect of the inhibiting current iscancelled by the current in an associated input wire.

In other embodiments employing switchable cores an input signal in aninput wire is adapted to switch the state of the cores, with which thewire is magnetically coupled, from a datum state to the alternativestate. Rectifiers are included in the output wires of the cores whichallow output pulses to fiow in the output wires only when the cores areswitched back from the alternative state to the datum state. The coresin the alternative state are switched back to the datum state atpredetermined instants by currents in the control wires and outputsignals are thus generated.

The invention will now be described, by way of example, with referenceto the accompanying drawings, in which:

FIG. 1 is a schematic circuit diagram of one embodiment of theinvention, and

FIG. 2 is a schematic circuit diagram of a second embodiment of theinvention.

Referring to FIG. 1, a translator comprises forty cores CS of saturable(non-rectangular loop) ferro-magnetic material. The cores are arrangedin four groups or rows of ten cores each, the cores being numbered 0, 1,2, 3, 4, 5, 6, 7, 8, 9 in each row. Each core is provided with an outputwire U individual thereto.

A number of input wires, of which four (A, B, C, D) are shown, eachthread one core from each of the four groups. The wire A threads thecore 2 from the first group, the core 4 from the second group, the core1 from the third group and the core 6 from the fourth group. Thus thewire A corresponds to the number 2, 4, 1, 6. The wires are connected torespective pulse sources S. The wire A is energised repetitively by thesource S connected thereto in order to obtain output pulsescorresponding to the digits 2, 4, 1, 6. However, the translator is soconstructed that the four digits of this number are obtained insuccession and not altogether. Thus, the cores CS in the four groupsrespectively are threaded by four control wires K1, K2, K3 and K4. Eachcontrol wire is connected to the output of a corresponding bi-stabledevice in the series F1 to F4. Each of these devices is such that whenin one state a current flows through the corresponding control wire,which current is of such mag nitude as to saturate all the coresthreaded by that control wire. When the bi-stable device is in the otherstate no current flows through the control wire.

Each bi-stable device has two inputs, one of which is connectedseparately to a pulse generator and the other of which is connected incommon to the pulse generator. The pulse generator provides a successionof pulses in the following manner. A set pulse P1 is applied to thebistable device Fl. This sets the bi-stable device F1 to its secondstate, leaving the bi-stable devices F2 to F4 in their first states.Accordingly, no current flows in the control wire K1, but current flowsin the control wires K2 to K4. On the application of a pulse from asource S to the wire A an output is induced in the output wire U of thecore 2 in the first group because the cores in this groups are in anunsaturated state. No output pulse is induced in the output wires of theother cores threaded by the wire A since the input pulse provided by thesource S only tends to drive these cores further beyond saturation,being of the polarity such as to cause this.

The pulse generator thereafter generates a pulse Q applied in common toall the bistable devices. This pulse is a resetting pulse and resets thebistable device F1 to its first state. A set pulse P2 is then applied tothe device F2, setting this to its second state. Accordingly, on theapplication of a further pulse in the wire A an output signal is inducedin the output wire of the core 4 in the second group. A further pulse Qresets the bi-stable device F2. A pulse P3 sets the bi-stable device F3,and the next pulse in the wire A induces an output in the output wire ofthe core 1 in the third group. After the application of a furtherresetting pulse Q a pulse P4 sets the bistable device F4 to its secondstate and a further pulse in the wire A induces an output in the outputwire of the core 6 in the fourth group. The pulse generator continues toproduce successions of pulses P1, P2, P3 and P4 with intervening pulsesQ and so causing each of the four different combinations of all controlwires but one, i.e., the four difierent combinations of three controlwires, to be energised in succession. Each time the four figure numbercorresponding to one of the wires A, B, C and so on is required asuccession of four properly timed pulses are provided by the source Sconnected to the selected wire.

In another mode of operation the sources S provide alternating currentsignals in the wires A, B, C and so on. If the currents in the controlWires are made of sufficient magnitude the alternating current signalswill be unable to desaturate the core which they thread and which isalso threaded by an energised control wire and, as in the previouslydescribed embodiment, an output signal will only be induced in theoutput winding of a core of the group whose control wire is notenergised.

Referring now to FIG. 2, there is shown a similar array of forty coreswhich are in this instance however, cores of a ferro-magnetic materialhaving a hysteresis loop of the shape known in the art as rectangular.The cores are again provided with individual output wires and aplurality of input wires A, B, C and so on. Each input wire threads onecore from each of the four groups of ten cores. Control wires K1, K2, K3and K4 are again provided. The bi-stable devices are replaced bytwogates G1, G2, G3, G4, energised by the pulse generator. The gates arearranged to produce outputs in succession in each cycle of operations.Thus, each gate has one input connected to a common lead L and anotherinput connected to a lead in a series L1 to L4 individual to the gate.The pulse generator provides a pulse P1 of relatively long duration inthe lead L and, in succession, pulses P2, P3, P4 and P5 in the leads L1to L4 respectively. A reset pulse is applied to a lead RR threading allforty cores following the application of each of the pulses P2 to P5. Onthe coincident application of pulses P1 and P2 to the gate G1 an outputpulse is provided in the lead K1. This is of half the amplitudenecessary to switch a core from the datum state to the alternativestate. Each source S provides a current in its associated input wire A,B, or C and so on, likewise of half the amplitude necessary to switchthe cores threaded by that wire from the datum state to the alternativestate. Accordingly, on the application of an input current in the wire Awhich, as will be seen, corresponds to the numher 2, 1, 4, 2, when thegate G1 produces an output pulse P2 an output signal is produced in theoutput wire of the core 2 in the first group. Thereafter a reset pulsein the lead RR resets this core to the datum state. The subsequentoutput pulse P3 from the gate G2 causes an output pulse to be induced inthe output wire of the core 1 in the second group. The subsequentapplication of further reset pulses and the pulses P4 and P5 causeoutput signals to be induced in the output wires of the core 4 in thethird group and the core 2 in the fourth group.

This embodiment may again be operated in alternative ways. For example,the pulse generator may energise the lead RR with a continuous currentof magnitude and sign such as to switch any core in the alternativestate to the datum state. The currents in the Wires A, B, C and so onare then made of sufficient magnitude to, by themselves, switch thecores threaded by the wires from the datum state to the alternativestate. The current puEs in the control wires 1(1 to K4 are made ofsimilar amplitude. Again, only a core threaded both by an energised wirein the Wires K1 to K4 and an energised input wire will have its stateswitched to the alternative state, therer i by inducing an output pulsein its output wire. The core thus switched is immediately returned tothe datum state by the continuing current in the lead RR when thecurrent pulse in the energised control wire ceases.

If required, the output wire of each core CS may be provided with arectifier in order that output pulses may only be passed when the coreschange from the datum state to the alternative state or from thealternative state to the datum state.

In a further embodiment the lead lRR is dispensed with. The currentsupply in the wires A, B, C and so on are made of suflicient amplitudeto switch all the cores threaded by the wire from the datum state to thealternative state. Rectifiers are included in each of the output wirescoupled to the cores and so poled that no current is passed when thecores are switched from the datum state to the alternative state. Theoutput pulses from the gates G1 to G4 are made of amplitude and signsuch that they return any core in the associated group in thealternative state to the datum state. Thus on the application of acurrent to the wire A the cores corresponding to the numher 2, 1, 4, 2are set to the alternative state. Pulses are provided in succession bythe gates G1, G2, G3, G4, resetting these cores to the. datum state inturn .and producing output pulses in their output wires in turn.

I claim:

1. An electrical code translator comprising a plurality N of groups ofcores of saturable, non-rectangular hysteresis loop ferro-magneticmaterial, a plurality of output wires individual to said coresrespectively, a plurality of input wires, each magnetically coupled to adifferent set of said cores, each said set including one core from eachgroup, a plurality N of control wires including one wire for each groupmagnetically coupled to all the cores of said group, a control circuitand means connecting said control circuit to said control wires, saidcontrol circuit comprising a plurality of energising means individual tosad control wires respectively for applying control signals to saidcontrol wires to drive all cores coupled to said wires to saturation ina predetermined sense and means for selectively controlling saidenergising means to apply control signals in succession to each of the Ndifferent combinations of control wires consisting of all said controlwires but one, the translator further comprising input means and meanscoupling said input means to said input wires, said input means applyinginput pulses to selected input wires in such a sense as to tend tomagnetise the sets of cores in said predetermined sense.

2. An electrical code translator according to claim 1 wherein saidcontrol circuit comprises a plurality of bistable circuits having outputterminals connected to said control wires respectively, each bi-stablecircuit applying a control signal to the control wire connected theretoin one state and applying no control signal to the control wireconnected thereto in the other state, the control circuit furthercomprising a pulse generator for providing 7 input pulses to saidbi-stable circuits fior selectively and sequentially setting them totheir first and second states. 3. An electrical code translatorcomprising a plurality N of groups of cores of saturable,non-rectangular hysteresis loop ferromagnetic material, a plurality ofoutput wires individual to said cores respectively, a plurality of inputwires, each magnetically coupled to a diiferent set of said cores, eachsaid set including one core from each group, a plurality N of controlwires including one wire for each group magnetically coupled to all thecores of said group, a control circuit and means connecting said controlcircuit to said control wires, said control circuit comprising aplurality of energising means individual to said control wiresrespectively for applying control signals to said control wires to driveall cores coupled to said wires beyond saturation in a predeterminedsense and means for selectively controlling said energising means toapply control signals in succession to each of the N differentcombinations of control wires consisting of all control wires but one,the translator further comprising input means and means coupling saidinput means to said input wires, said input means applying alternatinginput signals to selected input wires of magnitude less than thatsufiicient to desaturate said cores driven beyond saturation.

4. An electrical code translator comprising a plurality of groups ofcores of ferro-magnetic material, an individual output wire for each ofsaid cores magnetically coupled to the respective core, a plurality ofinput wires, each input wire being magnetically coupled to a set of saidcores, each said set of cores including one core from each group, andindividual control wire for each group of cores magnetically coupled toapply a magnetomotive force to all the cores of the respective group inresponse to a control signal in said wire, input means and meansconnecting said input means to the input wires whereby an input signalmay be applied to any selected one of said input wires to apply amagnetomotive force to each of the cores magnetically coupled to saidselective one of input wires, each said core being responsive to both aninput signal and a control signal in respective input and control wiresassociated with said core to cause an output signal to be generated inthe output wire for the core, and a control circuit means and meansconnecting said control circuit means to said control wires, saidcontrol circuit means being so constructed and operatively connected toapply control signals selectively to said control wires in predeterminedtimed relationship with respect to the input signals in the selectedinput wire to cause said output signals from the cores of the setcorresponding to the selected input wire and located in the differentgroups to be generated individually and selectively in timed sequence.

5. An electrical code translator according to claim 4, wherein saidcores are switchable cores and wherein said control circuit comprisesindividual energising means for applying currents in said control wiresof the sense and approximately half the magnitude necessary to switchthe cores from the datum state to the alternative state and means forselectively controlling said energising means to apply currents insequence to said control wires, said input means being so constructedand operatively connected for applying currents to selected input wiresof the sense and approximately half the magnitude necessary to switchthe cores from the datum state to the alternative state.

6. An electrical code translator according to claim 5, furthercomprising a reset wire coupled magnetically to all said cores and meansconnecting said reset wire to said control circuit, whereby said resetwire can be energised to return to the datum state each core set to thealternative state.

7. An electrical code translator according to claim 4 comprising aninhibit wire magnetically coupled to all said cores, means connectingsaid control circuit means to said inhibit wire, said control circuitmeans comprising individual energising means for applying currents insaid control wires of the sense and magnitude necessary to switch thecores from the datum state to the alternative state and means forselectively controlling said energising means whereby currents can beapplied to selected control wires, said control circuit means furthercomprising energising means for applying a current in said inhibit wireof the sense and magnitude necessary to switch the cores from thealternative state to the datum state, said input means being solelyconstructed and operatively connected for applying currents to selectedinput wires of the sense and magnitude necessary to switch the coresfrom the datum state to the alternative state.

8. An electrical code translator according to claim 4, wherein saidcontrol circuit means comprises a plurality of gating devices havingoutputs connected to said control wires respectively, and each having apair of input terminals, said control circuit means further comprising apulse generator adapted to apply a relatively long operat ing pulse toone input terminal of each gating device and during the application ofsaid pulse to apply a sequence of relatively short operating pulses tothe other inputs of said gating devices respectively, whereby saidcontrol wires are energised in succession and output signals from thedifferent cores of a set are generated only at times selected for eachof said groups respectively.

2,734,184 Rajchrnan Feb. 7, 1956 8 Abbott July 15, Auerbach July 22,Yetter Aug. 5, Miller Oct. 14, Lawrence Aug. 25, Buchholz et a1 Mar. 29,

FOREIGN PATENTS France Nov. 15, Great Britain Mar. 6,

4. AN ELECTRICAL CODE TRANSLATOR COMPRISING A PLURALITY OF GROUPS OF CORES OF FERRO-MAGNETIC MATERIAL, AN INDIVIDUAL OUTPUT WIRE FOR EACH OF SAID CORES MAGNETICALLY COUPLED TO THE RESPECTIVE CORE, A PLURALITY OF INPUT WIRES, EACH INPUT WIRE BEING MAGNETICALLY COUPLED TO A SET OF SAID CORES, EACH SAID SET OF CORES INCLUDING ONE CORE FROM EACH GROUP, AND INDIVIDUAL CONTROL WIRE FOR EACH GROUP OF CORES MAGNETICALLY COUPLED TO APPLY A MAGNETOMOTIVE FORCE TO ALL THE CORES OF THE RESPECTIVE GROUP IN RESPONSE TO A CONTROL SIGNAL IN SAID WIRE, INPUT MEANS AND MEANS CONNECTING SAID INPUT MEANS TO THE INPUT WIRES WHEREBY AN INPUT SIGNAL MAY BE APPLIED TO ANY SELECTED ONE OF SAID INPUT WIRES TO APPLY A MAGNETOMOTIVE FORCE TO EACH OF THE CORES MAGNETICALLY COUPLED TO SAID SELECTIVE ONE OF INPUT WIRES, EACH SAID CORE BEING RESPONSIVE TO BOTH AN INPUT SIGNAL AND A CONTROL SIGNAL IN RESPECTIVE INPUT AND CONTROL WIRES ASSOCIATED WITH SAID CORE TO CAUSE AN OUTPUT SIGNAL TO BE GENERATED IN THE OUTPUT WIRE FOR THE CORE, AND A CONTROL CIRCUIT MEANS AND MEANS CONNECTING SAID CONTROL CIRCUIT MEANS TO SAID CONTROL WIRES, SAID CONTROL CIRCUIT MEANS BEING SO CONSTRUCTED AND OPERATIVELY CONNECTED TO APPLY CONTROL SIGNALS SELECTIVELY TO SAID CONTROL WIRES IN PREDETERMINED TIMED RELATIONSHIP WITH RESPECT TO THE INPUT SIGNALS IN THE SELECTED INPUT WIRE TO CAUSE SAID OUTPUT SIGNALS FROM THE CORES OF THE SET CORRESPONDING TO THE SELECTED INPUT WIRE AND LOCATED IN THE DIFFERENT GROUPS TO BE GENERATED INDIVIDUALLY AND SELECTIVELY IN TIMED SEQUENCE. 